A conventional exhalation measurement device of this type is generally equipped with a flow regulator to obtain the exhalation flow that has been indicated for measuring nitrogen monoxide in exhalation. The function of this flow regulator is to accurately control the exhalation flow by automatically adjusting the flow of exhalation blown in through the inlet of the exhalation measurement device, or by adjusting the flow to a preset level.
This flow regulator also comprises a pressure sensor for controlling the flow very accurately. If the output of this pressure sensor changes over time, technology can be employed, for example, to perform zero point correction of the pressure sensor automatically as soon as the change in output goes over a specific set value, and prevent the occurrence of error in the measurement of pressure and flow.